1. Field of the Invention
The present invention relates to an optically integrated device, and more particularly, to an optically integrated device with a high luminous efficiency.
2. Description of the Prior Art
The optical system is improved as fast as the science develops. How to enhance the luminous efficiency, use low power consumption and remain the same volume of the optical system is very important. For example, the DLP (Digital Light Processing) image-processing system has the advantages of the high luminous efficiency and a small volume.
As shown in FIG. 1, the optical integrator 3 of the DLP image-processing system is a pillar with four side surfaces and two end surfaces. There is a rectangular light inputting face 5 on an end surface, and at the other end surface is a light outputting face 9. A reflective part 7 is distributed over the side surfaces. When the light L is emitted from the light source 1, a portion of the light L may directly penetrate through the optical integrator 3 to be filtered through a color wheel 11. The other portion of the light L that does not directly penetrate the optical integrator 3 is reflected by the reflective part 27 to penetrate the light outputting face 9, and to be filtered through the color wheel 11.
The rectangular light inputting face 5 adjusts the shape of the light L to project a rectangular image. If the shape of the cross-section of the light source 1 is circular, a portion of the light L, as the light L′, is lost. So that the luminous efficiency of the optical integrator is limited due to the lost light L′.
Moreover, a portion of the light L may be lost due to the color filter 11. As shown in FIG. 1, the light L is filtered through the color filter 11 to become the light L0, and is reflected by the color filter 11 to become the light L0′. The color of the light L0 and the area of the color wheel 11 that filtered the light L0 through is the same. Neither the reflected light L0′ and a small portion of the light L that is absorbed by the optical integrator 3 and the color wheel 11 are lost. Because the multiple colors are included in color wheel 11, the reflected light L0′ is lost which limits the luminous efficiency of the image-processing device.
An improved DLP image-processing device includes multiple DMDs (Digital Micromirror Devices) to enhance the luminous efficiency. The light L is separated by a plurality of prisms, which include a Red light, a Green light and a Blue light due to the different refractive indexes of the different primary colors. The image-processing device includes, multiple DMDs, which enhances the luminous efficiency, because most primary colors are projected on the DMDs to form the image. However, the DLP image-processing device including multiple DMDs enhances the luminous efficiency, the volume and the cost of the production at the same time.
According to the above description, it's necessary to develop an image-processing device with a higher luminous efficiency, a smaller volume and a more economical cost.